For some dental procedures, a combination of imaging modalities is used to image the procedure. For example, the subject's bones and teeth are typically imaged using an x-ray-based imaging modality, such as CT. Soft tissue and the other structures in the patient's mouth are imaged using MRI and/or optical imaging techniques, e.g., using digital cameras.
In order to facilitate the co-use of two or more imaging modalities for navigation during a dental procedure, and/or for planning a dental procedure, images acquired by the two modalities are typically registered to each other. Registration is a term that is used to describe one-to-one mapping between the coordinates in one space and those of another, such that points in the two spaces that correspond to the same anatomic point are mapped to each other (c.f., U.S. Pat. No. 5,769,789 to Wang).
In some procedures, in order to facilitate the co-registration of images acquired by two or more imaging modalities, fiducials are identified in images that have been acquired using respective modalities. The term “fiducial” is generally understood in engineering or surveying, to describe a point or marking, or a line, which is sufficiently precisely defined to serve as a standard or basis reference for other measurements (c.f., U.S. Pat. No. 5,603,318 to Heilbrun).
U.S. Pat. No. 6,319,006 to Scherer describes a method for producing a drill assistance device for a tooth implant that includes the process steps of, initially the taking of an x-ray picture of the jaw and the compilation of a corresponding measured data record; then a three-dimensional, optical measurement of the visible surfaces of the jaw and of the teeth and the compilation of a corresponding measured data record. The measured data records from the x-ray picture and the measured data records from the three-dimensional, optical image are correlated with each other. Based on the information that is now available the type and position of the implant relative to the adjacent teeth is planned and a drill template is produced which is attached to the neighboring teeth. This is described as making the exact drilling of the implant pilot hole possible.
US 2008/0057467 to Gittelson describes a prefabricated dental implant surgical guide. The implant surgical guide comprises a tooth-shaped contour which simulates a natural tooth shape and the final prosthesis. An impression of an edentulous area and existing teeth of a patient is taken. A stone model of the impression is then made. A tooth-shaped contour(s) is selected from a tooth-shape and size selector kit comprising tooth-shaped contours, the tooth-shaped contours having central bores and corresponding to the edentulous area are secured to the stone model. A matrix of the stone model is formed with the tooth-shaped contours in place. The matrix is then removed from the stone model while retaining the selected tooth-shaped contour(s). Surgical drill holes are created in the matrix aligned with the central bores of the selected tooth-shaped contours to create the implant surgical guide. The matrix, now functioning as a surgical guide is then placed into the mouth of the patient. An osteotomy site is initiated by placing a surgical drill bur through the surgical drill holes of the matrix and through the central bores of the selected tooth-shaped contours, while the selected tooth-shaped contours are stabilized in their proper position by the matrix. The tooth-shaped contours can also be made of a radio opaque material, which when contained in the matrix and worn by the implant patient allow it to function as a dental scan appliance.
The following references may be of interest:
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